Thin multi-layer panel structure

Abstract

The present invention relates to a multi-layer panel structure having a high gloss capping and a second high impact resistant thermoplastic polymer or composite layer, the multi-layer panel structure being for external and internal panel applications where chemical and / or scratch resistance is desired. The present invention also relates to a high gloss multi-layer panel which, once scratched, can be easily repaired to restore the surface gloss to at least 90% of the original surface gloss. The present invention further relates to an article made of the multi-layer panel structure of the present invention. The multi-layer structure can be used alone or can be very thin and used as a substitute for primer and coating on articles such as metal automotive parts.

Description

Technical Field

[0001] The present invention relates to a multi-layer panel structure having a first high gloss capping layer and a second high impact thermoplastic polymer or composite layer, the multi-layer panel structure being for exterior and interior panel applications where chemical resistance and / or scratch resistance are desired.

[0002] The present invention also relates to a high gloss multi-layer panel which, once scratched, can be easily repaired to restore the surface gloss to at least 90% of the original surface gloss.

[0003] The present invention further relates to an article made of the multi-layer panel structure of the present invention. The multi-layer structure can be used alone, or can be very thin and used as a substitute for primer and topcoat on articles such as metal automotive parts. Background Art

[0004] High gloss finishes are desirable in many articles including automotive interior and exterior, as well as in sports equipment and lawn and garden equipment. One problem with typical gloss paints and coatings is that the surface gloss layer is easily damaged due to scratching, abrasion, and chemical exposure. Once scratched, thin surface coatings are difficult to repair. In addition, many coatings involve the use of volatile organic solvents, which can cause health and / or environmental damage.

[0005] Certain structural plastics, such as high impact polystyrene (HIPS), acrylonitrile / butadiene / styrene (ABS) resins, poly(vinyl chloride) (PVC) resins, etc., exhibit attractive mechanical properties when extruded, molded, or formed into various articles. Although these structural plastics are strong, tough, and relatively inexpensive, the properties of their exposed surfaces are less than ideal. They are prone to degradation by light; may be susceptible to scratching; and may be attacked by common solvents.

[0006] The industry convention is to apply another resin material over the structural plastic to protect the underlying structural material and provide a surface that can withstand the abuse associated with the use environment. This surface material is called "capstock".

[0007] Capstock is generally much thinner than the structural plastic, typically about 10% to about 25% of the total thickness of the composite material including the capstock sheet layer and the structural plastic sheet layer. For example, the thickness of the capstock can be about 0.01 mm to 0.8 mm, preferably 0.0127 mm to 0.65 mm, and more preferably 0.04 mm to 0.38 mm, while the thickness of the structural plastic sheet layer can be about 1.0 mm to about 10 mm.

[0008] As a class, acrylic resins are known for their excellent optical properties, resistance to sunlight degradation, hardness, inertness to water and common chemicals, durability, and toughness, and are selected as capping materials for various structural plastics such as ABS sheets. The mechanical properties of the capping material are generally inferior to those of the structural plastic, but importantly, the capping material does not adversely affect the mechanical properties of the composite material.

[0009] Typical acrylic capping materials, such as those of Arkema, are described in US 6,852,405. These capping materials are generally impact-modified. The problem with impact-modified single acrylic sheets is that the impact modification reduces both the gloss and chemical resistance of the capping layer.

[0010] The capping material can be crosslinked to improve chemical resistance, but it is well known that it is difficult to make the crosslinked capping material thin enough to replace a painted finish.

[0011] US 5,975,625 and US 6,852,405 describe motor vehicle bodies having a single-layer plastic outer body and an internal metal frame.

[0012] Problem / Solution

[0013] There is a desire for a thin capping material having a very high gloss and high impact resistance, where the high gloss resists loss of gloss damage caused by surface contact with chemicals such as isopropyl alcohol, ethanol, methanol, sulfuric acid, phosphoric acid, toluene, isooctane, diisobutylene, and chemical mixtures such as gasoline fuel, diesel fuel, biofuel, asphalt, antifreeze, brake fluid, engine oil, pancreatic enzymes (bird guano substitute), tree resin, and sunscreen. The high gloss finish should also be easily restored to within 10% of the initial surface gloss.

[0014] It has surprisingly been found that a thin high gloss surface layer can be provided over a high impact resistance inner layer, which will minimize loss of gloss and enable the high gloss finish to be easily restored to within 10% of the original gloss.

[0015] Additional advantages of the present invention over conventional high gloss paints (used over a primer coat) in automotive applications include fewer manufacturing steps and elimination of volatile organic solvents associated with coating.

[0016] The multi-layer structure of the present invention can pass an 85°C exposure test and should be cost-competitive with conventional high gloss paints.

[0017] In addition, while it is difficult to handle and process typical crosslinked capping materials in which crosslinking occurs during polymerization, post-polymerization reactions (such as by radiation, such as UV radiation and electron beam radiation) can be used to form useful crosslinks. Summary of the Invention

[0018] In a first aspect, the present invention relates to a multi-layer polymer structure comprising a thin high-gloss outer capping layer having a 60° gloss greater than 80, preferably greater than 85, and more preferably greater than 90, as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter, wherein the capping layer has a thickness of 0.01 mm to 0.8 mm, preferably 0.0127 mm to 0.65 mm, and more preferably 0.04 mm to 0.38 mm; and an internal high-impact layer, wherein the high-impact layer has an ASTM D256 notched Izod result at 23 °C greater than 0.8 ft-lb / in, preferably greater than 1.0 ft-lb / in, and more preferably greater than 1.2 ft-lb / in.

[0019] In a second aspect, the thin high-gloss outer capping layer as described in the first aspect has a heat distortion temperature (HDT) of at least 175 °F, as measured by ASTM D648 (1.8 MPa) when the sample is annealed at 80 °C for 96 hours before measurement and then slowly cooled to 23 °C within 4 hours.

[0020] In a third aspect, the thin high-gloss outer capping layer as described in any of the previous two aspects contains at least one acrylic and / or styrene polymer as a matrix.

[0021] In a fourth aspect, the multi-layer polymer structure as described in any of the previous aspects contains less than 5 wt%, preferably less than 3 wt%, preferably less than 1 wt% of an impact modifier in the thin high-gloss outer capping layer, and most preferably does not contain an impact modifier.

[0022] In a fifth aspect, the thin high-gloss outer capping layer as described in any of the previous aspects has chemical resistance and scratch resistance, and has a light retention rate of more than 85%, preferably more than 90%, and a ΔE of less than 5, preferably less than 3, for each test material, and is tested using the following procedure: for a 6 x 6 inch sample, condition at 85 °C for one hour and rub back and forth ten times with a PIG Hazmat pad soaked with the test chemical, then wipe, clean, and re-condition with a clean PIG Hazmat pad for at least one hour, and re-measure the 60° gloss. The test chemicals used for rubbing are chemicals commonly found in sunscreen agents such as butylene glycol and glyceryl stearate. The cloth used in the test can be a 3 inch x 14 inch PIG Hazmat pad (MAT302) or a 3 inch x 14 inch PIG Hazmat pad (MAT423).

[0023] In a sixth aspect, the thin high-gloss outer capping layer as described in any of the foregoing aspects contains a polymer having a weight average molecular weight of at least 70,000 g / mol.

[0024] In a seventh aspect, the internal high-impact layer as described in any of the foregoing aspects is a thermosetting, thermoplastic, and / or polymer composite.

[0025] In an eighth aspect, the internal high-impact layer as described in any of the foregoing aspects has a thermoplastic as the matrix polymer, and the thermoplastic is selected from the group consisting of acrylonitrile butyl styrene (ABS), polyvinyl chloride (PVC), and high-impact polystyrene (HIPS), polycarbonate (PC), blends of acrylic polymers and polylactic acid, impact-modified acrylate resins, impact-modified styrenes, polycarbonate, thermoplastic polyolefin (TPO), polyamide, polyimide, polyester, polyurethane, polyolefin, and blends thereof.

[0026] In a ninth aspect, the high-impact layer as described in any of the foregoing aspects is a composite composition containing particles, nanoparticles, and / or fibers.

[0027] In a tenth aspect, the composite composition is a fiber-reinforced acrylic composite, and the composite is formed from a blend of one or more acrylic polymers having one or more acrylic monomers impregnated into the fibers and then polymerized.

[0028] In an eleventh aspect, the multilayer structure as described in any of the foregoing aspects further includes an intermediate layer or an adhesive layer located between the outer high-gloss layer and the internal high-impact layer.

[0029] In a twelfth aspect, the multilayer structure as described in any of the foregoing aspects is present on a substrate, and the substrate is selected from: metals; ceramics; and cellulose; thermoplastic, elastomeric, and thermosetting polymers, and the thickness thereof is in the range of 0.1 mm to 30 mm and preferably 1.0 mm to 5 mm.

[0030] In a thirteenth aspect, the multilayer structure as described in any of the foregoing aspects includes two high-gloss outer capping layers, one on each side of the internal high-impact layer.

[0031] In a fourteenth aspect, there is provided a method for restoring the gloss of a polymer multilayer structure as described in any of the foregoing aspects for chemical or physical abrasions, and the method includes the step of removing or hiding the abrasions.

[0032] In a fifteenth aspect, the method as described in aspect 14 involves scratch recovery by buffing, polishing, wiping, chemical treatment, and / or frosting the multilayer structure, wherein the glossiness is restored to within 30%, preferably within 20%, and most preferably within 10% of the original glossiness, as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85-degree gloss meter.

[0033] In a sixteenth aspect, the multilayer polymer structure as described in any of the foregoing aspects is manufactured by thermoforming, in-mold decoration, sequential injection molding, coextrusion, resin transfer molding with in-mold decoration, or 3D printing (additive manufacturing).

[0034] In a seventeenth aspect, an article is presented that includes a thin multilayer polymer structure as described in any of the foregoing aspects, wherein the article is selected from the group consisting of exterior panels, automotive body panels, automotive body trim, recreational vehicle body panels or trim, exterior panels for recreational sports equipment, marine equipment, exterior panels for outdoor lawn, garden, and agricultural equipment, and exterior panels for marine, aerospace structures, aircraft, public transportation applications, interior panel applications, interior automotive trim, interior panels for marine equipment, interior panels for aerospace and aircraft, interior panels for public transportation applications, and panels for electrical appliances, furniture, and cabinets. Detailed Description

[0035] As used herein, "copolymer" refers to a polymer having two or more different monomer units. "Polymer" is used to mean both homopolymers and copolymers. For example, as used herein, "PMMA" and "polymethyl methacrylate" are used to mean both homopolymers and copolymers, unless otherwise expressly stated. (Meth)acrylate is used to mean both acrylate and methacrylate, and mixtures thereof. The polymer can be linear, branched, star-shaped, comb-shaped, blocky, or any other structure. The polymer can be homogeneous, heterogeneous, and can have a gradient distribution of comonomer units. All cited documents are incorporated herein by reference.

[0036] As used herein, unless otherwise described, percentages shall refer to weight percentages.

[0037] The molecular weight is the weight-average molecular weight as measured by GPC. In cases where the polymer contains some crosslinking and GPC cannot be applied due to insoluble polymer fractions, the molecular weight of the soluble fraction / gel fraction or the molecular weight of the soluble fraction after extraction from the gel is used.

[0038] As used herein, "multi-layer" describes a structure having at least two layers attached directly or indirectly to each other, where the outer layer is a high-gloss capping material and at least one inner layer is a high-impact layer. These layers can be in direct contact with each other or can contain one or more other layers therebetween, such as a tie layer, an adhesive layer, a vapor barrier layer, a color layer, or a special effect layer, etc. In one embodiment, the multi-layer structure has a high-gloss capping material on either side of the inner high-impact layer. This arrangement is particularly useful when the multi-layer structure is transparent or translucent and the surfaces on both sides will be visible.

[0039] Outer high-gloss layer

[0040] The outer high-gloss layer is an acrylic- and / or styrene-based layer; it has chemical resistance, scratch resistance, and abrasion resistance, and any degradation of the high gloss can be restored to within 10% of the original gloss. The 60° gloss of the outer layer is greater than 80, preferably greater than 85, and more preferably greater than 90, as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter.

[0041] The outer high-gloss layer can optionally contain 0.01 wt% to 20 wt% of a nano-scale particulate additive to improve chemical resistance, scratch resistance, abrasion resistance, and / or the ability of the high-gloss surface to recover after being damaged by chemical exposure, scratching, and / or abrasion. Useful nano-scale inorganic fillers include, but are not limited to, silica, alumina, zinc oxide, barium oxide, molybdenum disulfide, boron nitride, tungsten disulfide, titanium oxide, nano-graphene, nano-graphite, nano-graphite flakes, and graphite oxide nanoparticles.

[0042] The outer high-gloss layer is thin, having a thickness of 0.01 mm to 0.8 mm, preferably 0.0127 mm to 0.65 mm, and more preferably 0.04 mm to 0.38 mm.

[0043] The outer high-gloss layer has a heat distortion temperature (HDT) greater than 175°F (or 80°C), as measured by ASTM D648 (1.8 MPa) when annealing the sample at 60°C - 80°C for 96 hours and then slowly cooling it to 23°C over 4 hours.

[0044] The acrylic or styrene polymer of the present invention has a weight average molecular weight between 50,000 g / mol and 500,000 g / mol, and preferably between 70,000 g / mol and 200,000 g / mol, as measured by gel permeation chromatography. The molecular weight distribution of the acrylic polymer can be unimodal or multimodal, where the dispersity index is greater than 1.5. Copolymers containing comonomers that would reduce the HDT of the copolymer such as C 1-6The copolymer of acrylate should have a weight-average molecular weight greater than 100,000 g / mol. In a preferred embodiment, the acrylic capping layer will mainly contain methyl methacrylate monomer units and have less than 10 wt%, and preferably less than 5 wt%, of comonomers. The acrylic capping material may also have comonomers such as methacrylic acid, tert-butyl cyclohexyl methacrylate, α-methylstyrene, and other monomers that increase T g of the comonomers, where the total comonomer content can be up to 25%.

[0045] In one embodiment, the capping layer is a blend of an acrylic or styrene polymer with up to 90 wt%, preferably less than 60 wt%, more preferably less than 35 wt%, of a polyvinylidene fluoride (PVDF) homopolymer or copolymer. A blend of an acrylic polymer with less than 30 wt%, preferably less than 20 wt%, of polylactic acid can also be used. The high-gloss acrylic capping material can also be a crosslinked acrylic sheet having less than 5% of a crosslinking agent.

[0046] In one embodiment, the outer high-gloss layer can be a polymer blend that contains an acrylic or styrene polymer plus up to 60 wt%, preferably up to 40 wt%, of one or more other compatible, miscible, or semi-miscible polymers. A useful blend is a blend of a poly(meth)acrylic acid polymer or copolymer with an acrylonitrile-styrene-acrylate (ASA) polymer.

[0047] In one embodiment, crosslinking is provided by a post-polymerization reaction such as by using radiation. Useful radiations include UV radiation, gamma radiation, and electron beam. By using a post-polymerization crosslinking mechanism, a thinner capping layer that can be easily processed can be achieved.

[0048] As used herein, "acrylic polymer" is intended to include polymers, copolymers, and terpolymers formed from alkyl methacrylate and alkyl acrylate monomers and mixtures thereof. The alkyl methacrylate monomer is preferably methyl methacrylate, which may constitute 50% to 100% of the monomer mixture. Other acrylate and methacrylate monomers or other ethylenically unsaturated monomers (including but not limited to styrene, α-methylstyrene, acrylonitrile) and low levels of crosslinking agents may also be present in the monomer mixture at 0% to 50%. Other methacrylate and acrylate monomers that may be used in the monomer mixture include but are not limited to methyl acrylate, ethyl acrylate and ethyl methacrylate, butyl acrylate and butyl methacrylate, isooctyl acrylate and methacrylate, n-octyl acrylate, lauryl acrylate and lauryl methacrylate, stearyl acrylate and stearyl methacrylate, borneol acrylate and methacrylate, methoxyethyl acrylate and methacrylate, 2-ethoxyethyl acrylate and methacrylate, isodecyl acrylate and methacrylate, tert-butylcyclohexyl acrylate and methacrylate, tert-butylcyclohexanol methacrylate, trimethylcyclohexyl acrylate and methacrylate, methoxy polyethylene glycol acrylate and methacrylate having 2-11 ethylene glycol units, phenoxyethyl acrylate and methacrylate, alkoxylated phenyl acrylate, ethoxylated phenyl acrylate and methacrylate, glycidyl methacrylate, tetrahydrofurfuryl acrylate and methacrylate, alkoxylated tetrahydrofurfuryl acrylate, trimethylolpropane formal acrylate, caprolactone acrylate, dimethylaminoethyl acrylate and methacrylate monomers. Alkyl (meth)acrylic acids such as methacrylic acid and acrylic acid or their C1-C8 esters may be used in the monomer mixture. Alkyl (meth)acrylic acids such as methacrylic acid and acrylic acid may be used in the monomer mixture. Most preferably, the acrylic polymer is a copolymer having 85 wt% to 99.5 wt% of methyl methacrylate units and 0.5 wt% to 15 wt% of one or more C 1-8 linear or branched alkyl acrylate units.

[0049] Styrene-based polymers include, but are not limited to, polystyrene, high-impact polystyrene (HIPS), acrylonitrile-butadiene-styrene (ABS) copolymer, acrylonitrile-styrene-acrylate (ASA) copolymer, styrene acrylonitrile (SAN) copolymer, methacrylate-butadiene-styrene (MBS) copolymer, styrene-butadiene copolymer, styrene-butadiene-styrene block (SBS) copolymer and its partially or fully hydrogenated derivatives, styrene-isoprene copolymer, styrene-isoprene-styrene (SIS) block copolymer and its partially or fully hydrogenated derivatives, and styrene-(meth)acrylate copolymers such as styrene-methyl methacrylate copolymer (S / MMA). The preferred styrene polymer is ASA. The styrene polymers of the present invention can be manufactured by means known in the art including emulsion polymerization, solution polymerization, and suspension polymerization. The styrene copolymers of the present invention have a styrene content of at least 10% by weight, preferably at least 25% by weight.

[0050] The capping material should contain less than 15% by weight, preferably less than 5% by weight, more preferably less than 3% by weight, and most preferably less than 1% by weight of an impact modifier. In a preferred embodiment, the capping layer does not contain an impact modifier.

[0051] Inner high-impact layer

[0052] The thin multi-layer panel structure of the present invention has at least one high-impact inner layer. This can be an impact-resistant thermoplastic, a blend of thermoplastics (where the blend exhibits impact resistance), a blend of one or more thermoplastics with one or more thermoplastic elastomers and / or thermoplastic vulcanizates (where the blend exhibits impact resistance), a thermosetting polymer, or a polymer composite. The high-impact layer has an ASTM D256 notched Izod result at 23 °C greater than 0.8 ft-lb / in, preferably greater than 1.0 ft-lb / in, and more preferably greater than 1.2 ft-lb / in.

[0053] Useful impact-resistant thermoplastics include, but are not limited to, acrylonitrile butyl styrene (ABS), polyvinyl chloride (PVC), and high-impact polystyrene (HIPS), polycarbonate (PC), blends of acrylic polymers and polylactic acid, impact-modified acrylate resins such as those from Arkema impact-modified styrene, polycarbonate, thermoplastic polyolefin (TPO), poly(phenylene oxide), polyphenylene ether, polystyrene polyamide, polyimide, polyester, polyolefin, and blends thereof. The preferred thermoplastics are ABS and polycarbonate.

[0054] Useful composite materials include, but are not limited to, those reinforced with particles or nanoparticles (including, but not limited to, graphite, carbon nanotubes, and silica); and / or those reinforced with fibers (including, but not limited to, glass fibers, carbon fibers, and natural fibers) in thermoplastic and thermosetting resins. The particles and / or nanoparticles may have a mechanical modulus greater than or less than the continuous phase. The fibers may be in the form of single fibers, woven fibers, and woven or non-woven mats. Thermoplastic composite materials include those with matrices of ABS, PVC, HIPS, acrylic polymers, polyamides, polyurethanes, styrene, polyether ketone ketone, and polyether ether ketone. Useful thermosetting matrices include, but are not limited to, polyester or epoxy resins.

[0055] In one embodiment, a composite material is formed using an acrylic liquid resin system containing a blend of acrylic monomers, acrylic polymers, and an initiator. The liquid resin system is used to impregnate fibers, followed by polymerization. Resins from Arkema are useful examples of such systems.

[0056] In one embodiment, the internal high impact resistant polymer is a blend of an acrylic resin and a polyester (such as polylactic acid).

[0057] The thickness of the entire multi-layer structure depends on the final application of the structure, but is generally in the range of 0.1 mm to 30 mm, and preferably 1.0 mm to 5 mm.

[0058] Manufacture

[0059] The multi-layer structure of the present invention can be manufactured by several different means known in the art. The structure can be formed by co-extrusion, extrusion lamination, extrusion coating, in-mold decoration, sequential injection molding, thermoforming of co-extruded sheets or cast sheets, RTM-TS (resin transfer molding and in-mold decoration), and 3D printing (additive manufacturing).

[0060] Properties

[0061] The thin multi-layer structure of the present invention has several properties that make it particularly useful in many applications.

[0062] The high gloss capping has a 60° gloss greater than 80, preferably greater than 85, and more preferably greater than 90, as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter.

[0063] The high gloss capping is resistant to chemicals, abrasion, scratching, cracking, and color shift, as well as loss of gloss. For opaque colored samples, the most significant appearance change after surface chemical exposure is loss of gloss, which is used in the present invention to characterize chemical damage and successful recovery.

[0064] The gloss of the high-gloss cap can be easily restored in case of damage. Since the capping layer is thicker than typical coatings, additional material needs to be removed to restore the surface aesthetics. The surface aesthetics can be restored by polishing, which is not achievable for painted surfaces. Other means of promoting restoration include, but are not limited to, buffing, wiping, chemical treatment, and / or sanding.

[0065] The structure can be transparent or translucent, which is not possible for painted cars or other types of panels.

[0066] Applications / Uses

[0067] The multi-layer structure of the present invention is an excellent material for use in many applications and articles due to its excellent gloss, scratch and abrasion resistance, and ability to restore gloss. These applications and articles include, but are not limited to, interior and exterior panels, automotive body panels, automotive body trim, recreational vehicle body panels and trim, exterior panels for recreational sports equipment, marine equipment, exterior panels for outdoor lawns, gardens, and agricultural equipment, and exterior panels for marine, aerospace structures, aircraft, public transportation applications, interior panel applications, interior automotive trim, interior panels for marine equipment, interior panels for aerospace and aircraft, interior panels for public transportation applications, and panels for electrical appliances, furniture, and cabinets.

[0068] In this specification, embodiments have been described in a manner that enables a clear and concise specification to be written, but it is intended and will be understood that the embodiments can be combined or separated in various ways without departing from the present invention. For example, it will be understood that all of the preferred features described herein apply to all aspects of the present invention described herein.

[0069] Examples

[0070] Chemical resistance test method

[0071] In this test, chemicals commonly found in sunscreens such as butylene glycol and glyceryl stearate were applied to the plastic surface. The high-gloss acrylic capping material surface was exposed to the sunscreen chemicals at 85 °C for 30 minutes and 24 hours. The detailed test method is as follows: For 6x6 inch samples, condition at 85 °C for one hour and rub back and forth ten times with a PIG Hazmat pad soaked with the test chemical, then wipe, clean, and re-condition with a clean PIG Hazmat pad for at least one hour and re-measure the 60° gloss. The test chemicals used for rubbing are a mixture of butylene glycol and glyceryl stearate commonly found in sunscreens. The cloth used in the test can be a 3-inch x 14-inch PIG Hazmat pad (MAT302) or a 3-inch x 14-inch PIG Hazmat pad (MAT423).

[0072] After chemical exposure at the specified temperature, the sample is cooled and stabilized at room temperature for one hour, then washed with deionized water and wiped clean. The initial surface gloss and the final surface gloss are characterized by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85-degree gloss meter and the 60° gloss (measured parallel to the direction of friction) is recorded. The measurement units comply with the standards of DIN 67530, ISO 2813, ASTM D 523, and BS 3900 Part D5. The reported value is the percentage of the surface gloss retained after chemical exposure.

[0073] Polishing method

[0074] The high-gloss acrylic surface is buffed and polished by the following method. Animal fat and rouge are applied to a cotton buffing wheel. The sample is buffed for 30 - 240 seconds with a slight pressure below the axis of the wheel; sufficient pressure is applied to make the wheel rub across the surface of the sample. After the buffing step, a cotton flannel polishing wheel is used to apply a slight pressure to the sample for 10 seconds to further smooth the surface. After buffing and polishing, the acrylic surface is cleaned with soap and water and then dried with a cotton cloth.

[0075] Scratch test method

[0076] The high-gloss acrylic surface is scratched according to the following method. A 6-inch × 6-inch injection-molded high-gloss acrylic resin plate is conditioned for 48 hours at 23 ± 1 °C and 50 ± 5% relative humidity. Then, on a Taber multi-finger scratch tester model 710, the surface is scratched with a spherical indentor with a radius of curvature of 1 ± 0.1 mm and a 15 N scratch load. The scratch speed is 100 ± 5 mm / s, and the scratch length is 140 mm.

[0077] Paper polishing method

[0078] Within 1 hour after scratching, the samples exposed to scratch damage are paper-polished by the following method. A 4-inch × 4-inch polishing paper (3M TM 281Q Wetordry TM 2-micron polishing paper) is wrapped around a dense sponge. Using a slight pressure and a circular polishing motion, the scratched acrylic surface is continuously hand-polished with the polishing paper for 5 minutes. After paper-polishing, the acrylic surface is cleaned with soap and water and then dried with a cotton cloth. The 20 surface gloss of the non-scratched area of the plate is measured before and after paper-polishing using a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85-degree gloss meter as described above.

[0079] Scratch visibility analysis

[0080] The visibility of scratch damage was quantified by an optical microscopy method. Digital images of the surface scratch area were captured at 100x magnification in bright-field mode using a Nikon ME600 optical microscope equipped with a Pixelink PL-D685 color camera. The images were converted to the RGB color format, in which each pixel color was represented by the R, G, and B values (integer values from 0 to 255) of the red, green, and blue components of the pixel color according to the RGB color system. Then, the R, G, and B values were measured for each pixel within two analysis regions A and B of the same size and dimensions. Region A was completely contained within the scratch area, and region B was adjacent to region A and completely contained within the non-scratch area. Both regions must contain an area greater than 1000 pixels. For each region, the average R, G, and B values of all pixels were calculated. Finally, the scratch visibility value was calculated according to the following formula:

[0081] Scratch visibility value = |[(R A + G A + B A ) / 3] - [(R B + G B + B B ) / 3]|

[0082] where RA, GA, and BA are the average red, green, and blue values of all pixels in region A, respectively. Similarly, RB, GB, and BB are the average red, green, and blue values of all pixels in region B, respectively. Therefore, the scratch visibility increases as the scratch visibility value increases.

[0083] Gloss recovery after chemical exposure damage in Example 1

[0084] Chemicals commonly found in sunscreens such as butylene glycol and glyceryl stearate can cause significant damage to acrylic materials at high temperatures (85 °C). This example demonstrates the removal of surface damage and / or surface residues and the restoration of surface gloss and color. Table 1 shows the light retention rate before and after polishing for 30 ± 10 seconds. Before polishing, the acrylic material was exposed to a sunscreen containing a mixture of butylene glycol and glyceryl stearate as the main components at 85 °C for 24 hours using the chemical resistance test method described above. After the initial 30 ± 10 seconds of polishing, the surface gloss of the high-gloss acrylic capping material can be restored to at most 80% of the original 60° surface gloss. To restore the high-gloss surface to 90% of the original gloss, repeated polishing was performed as shown in Table 2, where a total polishing time of 2 minutes can restore the gloss to within 10% of the original gloss.

[0085] Table 1: Light retention rate before and after polishing for 30 ± 10 seconds after chemical exposure damage (samples were exposed to sunscreen at 85 °C for 24 hours)

[0086]

[0087] Sample 1 = a transparent PMMA / EA copolymer having an EA comonomer content of 1 wt% to 10 wt% and a weight-average molecular weight in the range of 70,000 g / mol to 110,000 g / mol.

[0088] Sample 2 = a transparent PMMA / EA copolymer having an EA comonomer content of 1 wt% to 10 wt% and a weight-average molecular weight in the range of 100,000 g / mol to 200,000 g / mol.

[0089] Sample 3 = a transparent PMMA / EA copolymer having an EA comonomer content of 1 wt% to 10 wt% and a weight-average molecular weight in the range of 70,000 g / mol to 110,000 g / mol, said transparent PMMA / EA copolymer having an impact modifier in an amount of 10 wt% to 35 wt% based on the weight of the PMMA / EA copolymer.

[0090] Sample 4 = a transparent PMMA / EA copolymer having an EA comonomer content of 1 wt% to 10 wt% and a weight-average molecular weight in the range of 70,000 g / mol to 110,000 g / mol, said transparent PMMA / EA copolymer having an impact modifier in an amount of 30 wt% to 60 wt% based on the weight of the PMMA / EA copolymer.

[0091] Sample 5 = a black PMMA / EA copolymer having an EA comonomer content of 1 wt% to 10 wt% and a weight-average molecular weight in the range of 70,000 g / mol to 110,000 g / mol, said black PMMA / EA copolymer having an impact modifier in an amount of 0.5 wt% to 15 wt% based on the weight of the PMMA / EA copolymer.

[0092] Table 2: Glossiness change of Sample 3 after repeated polishing

[0093] Total time (minutes) Gloss (60°) Gloss retention rate 0 4.8 5.54％ 0.5 50.3 58.1％ 1.0 64.7 74.7％ 2.0 80.5 93.0％ 3.0 79.6 91.9％ 4.0 80.8 93.3％

[0094] Example 2: Chemical resistance test

[0095] According to the described chemical resistance test method, samples of the acrylic capping material were exposed to a light-shielding agent at 85 °C.

[0096] Sample 6 is a black PMMA / EA copolymer having an EA comonomer content of 0.1 wt% to 2.0 wt% and a weight-average molecular weight in the range of 70,000 g / mol to 110,000 g / mol.

[0097] Sample 7 is a black PMMA / MAA copolymer with an MAA comonomer content of 1 wt% to 10 wt% and a weight average molecular weight in the range of 70,000 g / mol to 110,000 g / mol.

[0098] Two samples were tested in duplicate, and both samples exhibited a light retention rate of over 90% and minimal color change (ΔE less than 3), as shown in Table 3.

[0099] Table 3

[0100] Sample Initial gloss Gloss after exposure Gloss retention rate of 60° gloss ΔE 6 86.4 90.7 104.9％ 2.16 6 86.1 92.8 107.8％ 2.48 7 87.2 85.5 98.1％ 0.44 7 87.6 85.9 98.1％ 0.41

[0101] Example 3: Surface recovery after scratch damage

[0102] External panels often suffer surface damage due to scratching and abrasion. This example demonstrates the utility of scratch-resistant formulations (such as those described in WO18132818 A3) for the outer layer of high-gloss external panels. It also demonstrates the recovery of the surface via paper polishing after scratch damage. A 6-inch × 6-inch sample plate was prepared by injection molding and then attached to a steel plate for scratch testing and paper polishing. The sample was scratched according to the above scratch test method and then paper polished according to the above paper polishing method. The scratch visibility and surface gloss before and after paper polishing are listed in Table 4.

[0103] Sample 8 is a black PMMA / EA copolymer with an EA comonomer content of 0.1 wt% to 2.0 wt% and a weight average molecular weight in the range of 70,000 g / mol to 110,000 g / mol.

[0104] Sample 9 is the same as Sample 8, with 15 wt% of Cabot TS622 fumed silica added. Sample 9 was prepared by melt compounding the black PMMA / EA copolymer and Cabot TS622 fumed silica on a 27-mm Leistritz ZSE-27HP twin-screw extruder.

[0105] The initial gloss of Sample 8 and Sample 9 was above 85 points for 60° gloss and above 78 points for 20° gloss, despite the presence of nanoparticle reinforcement in Sample 9. After scratching, the scratch visibility of Sample 8 (38.1) was significantly greater than that of Sample 9 (5.6). Visually, the scratch visibility of Sample 8 also appeared more severe than that of Sample 9. After paper polishing, the gloss of both Sample 8 and 9 decreased; however, the gloss retention rate of Sample 9 (98%) was greater than that of Sample 8 (76%). The scratch visibility of both samples decreased after paper polishing, with the greatest decrease in Sample 8. Sample 8 exhibited a relatively low 20° gloss retention rate (76%) after paper polishing. Sample 9 demonstrated a useful combination of high initial gloss, low scratch visibility before and after paper polishing, and excellent (98%) 20° gloss retention rate after paper polishing.

[0106]

[0107] Using low heat build-up colorants, such as IR reflective pigments or IR transmissive organic dyes, the heat build-up (plastic temperature rising above ambient temperature) of dark acrylic capping materials can be reduced by up to 30°F (determined using ASTM D4803). Accordingly, the service temperature of an exterior panel with IR reflective pigments or IR transmissive organic dyes will be much lower than that of an exterior panel without IR reflective pigments or IR transmissive organic dyes. The lower service temperature can improve chemical resistance by reducing the thermodynamic mixing free energy between the polymeric exterior panel and the chemicals to which the polymeric substrate is exposed. Accordingly, the lower service temperature can significantly mitigate the ingress of chemicals into the exterior panel, retard potential degradation caused by these chemicals, and reduce the temperature difference between the layers within the exterior panel, which can be a multi-layer structure, to minimize the likelihood of delamination failure within the exterior panel. The lower service temperature can also reduce the temperature difference between the exterior panel and any support material (such as metal) to which the exterior panel can adhere to minimize the likelihood of adhesive interface delamination failure.

Claims

1. A multi-layer polymer structure, comprising: a. A thin high-gloss outer polymer capping layer having a 60° gloss greater than 80 as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter, wherein the capping layer has a thickness of 0.01 mm to 0.8 mm, and wherein the thin high-gloss outer polymer capping layer comprises a PMMA / EA copolymer having a weight average molecular weight in the range of 70,000 to 110,000 g / mol and an EA comonomer content of 1 wt% to 10 wt%; and b. An internal high-impact layer having an ASTM D256 notched Izod result at 23 °C greater than 0.8 ft-lb / in.

2. The multi-layer polymer structure according to claim 1, wherein the capping layer has a 60° gloss greater than 85 as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter.

3. The multi-layer polymer structure according to claim 1, wherein the capping layer has a 60° gloss greater than 90 as measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85 degree gloss meter.

4. The multi-layer polymer structure according to claim 1, wherein the capping layer has a thickness of 0.0127 mm to 0.65 mm.

5. The multi-layer polymer structure according to claim 1, wherein the capping layer has a thickness of 0.04 mm to 0.38 mm.

6. The multi-layer polymer structure according to claim 1, wherein the internal high-impact layer has an ASTM D256 notched Izod result at 23 °C greater than 1.0 ft-lb / in.

7. The multi-layer polymer structure according to claim 1, wherein the internal high-impact layer has an ASTM D256 notched Izod result at 23 °C greater than 1.3 ft-lb / in.

8. The multi-layer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer has a heat distortion temperature (HDT) of at least 175 °F as measured by ASTM D648 at 1.8 MPa when the sample is annealed at 80 °C for 96 hours before measurement and then slowly cooled to 23 °C within 4 hours.

9. The multi-layer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer contains less than 5 wt% of an impact modifier.

10. The multi-layer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer contains less than 3 wt% of an impact modifier.

11. The multi-layer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer contains less than 1 wt% of an impact modifier.

12. The multi-layer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer does not contain an impact modifier.

13. The multilayer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer further comprises from 0 wt% to 20 wt% of nanoparticles.

14. The multilayer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer further comprises from 10 wt% to 15 wt% of nanoparticles.

15. The multilayer polymer structure according to claim 13, wherein the nanoparticles are selected from the group consisting of: silica, alumina, zinc oxide, barium oxide, molybdenum disulfide, boron nitride, tungsten disulfide, titanium oxide, nanographene, nanographite, and graphite oxide nanoparticles.

16. The multilayer polymer structure according to claim 15, wherein the nanographite comprises nanographite flakes.

17. The multilayer polymer structure according to claim 1, wherein the thin high-gloss outer polymer capping layer has chemical resistance and scratch resistance, with a light retention rate of more than 85% and a ΔE of less than 5, and is tested according to the following procedure for each test material: for a 6×6 inch sample, conditioned at 85 °C for one hour and rubbed back and forth ten times with each test material, then wiped, cleaned, and re-conditioned for at least one hour, and the 60° glossiness is re-measured. The test material for rubbing is made by immersing the chemicals commonly found in sunscreen agents into a fabric, and the fabric is a 3-inch × 14-inch PIGHazmat mat MAT302.

18. The multilayer polymer structure according to claim 17, wherein the thin high-gloss outer polymer capping layer has a light retention rate of more than 90% and a ΔE of less than 3.

19. The multilayer polymer structure according to claim 17, wherein the chemicals commonly found in sunscreen agents comprise butylene glycol and glyceryl stearate.

20. The multilayer polymer structure according to claim 1, wherein the inner high-impact layer is a thermosetting, thermoplastic, and / or polymer composite.

21. The multilayer polymer structure according to claim 1, wherein the inner high-impact layer comprises a thermoplastic selected from the group consisting of: acrylonitrile butyl styrene (ABS), polyvinyl chloride (PVC), and high-impact polystyrene (HIPS), polycarbonate (PC), blends of acrylic polymers and polylactic acid, impact-modified acrylate resins, impact-modified styrene, thermoplastic polyolefin (TPO), polyamide, polyimide, polyurethane, polyester, polyolefin, and blends thereof.

22. The multilayer polymer structure according to claim 21, wherein the inner high-impact layer is a composite composition containing particles and / or fibers.

23. The multilayer polymer structure according to claim 22, wherein the particles comprise nanoparticles.

24. The multilayer polymer structure according to claim 22, wherein the composite composition is a fiber-reinforced acrylic composite, and the composite is formed from a blend of one or more acrylic polymers having one or more acrylic monomers impregnated into the fibers and then polymerized.

25. The multilayer polymer structure according to claim 1, wherein the structure further comprises an adhesive layer and a tie layer located between the thin high-gloss outer polymer capping layer and the internal high-impact layer.

26. A multilayer polymer structure comprising the multilayer polymer structure according to claim 1 over a substrate, wherein the substrate is selected from the group consisting of: metal; ceramic; cellulose; thermoplastic, elastomeric, and thermosetting polymers, having a thickness in the range of 0.1 mm to 30 mm.

27. The multilayer polymer structure according to claim 26, wherein the substrate has a thickness in the range of 1.0 mm to 5 mm.

28. The multilayer polymer structure according to claim 1, wherein the structure comprises two thin high-gloss outer polymer capping layers, one on each side of the internal high-impact layer.

29. The multilayer polymer structure according to claim 1, wherein the structure is manufactured by thermoforming, in-mold decoration, sequential injection molding, coextrusion, resin transfer molding with in-mold decoration, or 3D printing.

30. A method for restoring the gloss of the multilayer polymer structure according to claim 1 for chemical or physical abrasions, wherein the method comprises the step of removing or hiding the abrasions.

31. The method according to claim 30, wherein the gloss is restored by sanding, polishing, wiping, chemical treatment, and / or frosting the multilayer polymer structure, wherein the gloss measured by a BYK Gardner Micro-Tri-Gloss 20 / 60 / 85-degree gloss meter is restored to within 30% of the original gloss.

32. The method according to claim 31, wherein the gloss is restored to within 20% of the original gloss.

33. The method according to claim 31, wherein the gloss is restored to within 10% of the original gloss.

34. An article comprising the multilayer polymer structure according to claim 1, wherein the article is selected from the group consisting of: exterior panels and interior panels.

35. The article according to claim 34, wherein the exterior panel comprises an exterior panel for mass transit applications, and the interior panel comprises an interior panel for mass transit applications.

36. An article comprising the multilayer polymer structure according to claim 1, wherein the article is selected from the group consisting of: automotive body panels, automotive body trim, recreational vehicle body panels and trim, exterior panels for recreational sports equipment, marine equipment, exterior panels for outdoor lawns, gardens, and agricultural equipment, and exterior panels for ships, aerospace structures, aircraft, interior automotive trim, interior panels for marine equipment, interior panels for aerospace and aircraft, and panels for appliances, furniture, and cabinets.

Images